Quantitative analysis of concrete property under effects of crack, freeze-thaw and carbonation

Bridge structures are exposed to vehicle loading and aggressive environments, damage of concrete will inevitably occur. In this study, influences of crack, freeze-thaw (F-T) cycling and carbonation on mechanical property and durability of reinforced concrete were investigated. Concrete prism specimens with rebars were prepared. Corresponding experimental arrangement was obtained based on orthogonal design method, and nine groups of reinforced concrete samples were tested. These samples were firstly loaded to produce cracks with different widths. Secondly, they were retained in cyclic F-T testing machine. Spalling mass and compressive strength were measured and evaluated for concrete under different crack widths and F-T cycles. Then concrete samples were exposed to carbon dioxide (CO2) gas pressure. Finally, chloride induced corrosion of rebar was tested and combined effects of crack, F-T cycling and carbonation on rebar corrosion were demonstrated based on range analysis (RA), analysis of variance (ANOVA) and Spearman's rank correlation coefficient method (SRCCM), respectively. The results reveal that crack and F-T cycles all increase the spalling mass of concretes, whereas reduce their compressive strength. Crack presents more significant effect on rebar corrosion compared with F-T cycles and carbonation.